If you're on a budget, try building one of these:http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf
For the 432 MHz designs you can shorten the elements 1/2" to move them to the
440 - 450 MHz range and use the existing element spacings.
The 11-element version has a 60" boom, excellent Front-to-Back ratio and good
gain, and they are very easy to build.